Marker holder



FIG. 1 is a top, left front perspective view of a marker holder showing our new design;

FIG. 2 is a left side elevational view;

FIG. 3 is a right side elevational view;

FIG. 4 is a top plan view;

FIG. 5 is a front elevational view, the rear view being a mirror image thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a marker holder, as shown and described. 